1. Field of the Invention
The present invention relates to mobile phone handset software and, more particularly, to preventing simultaneous data and voice channel transmissions in dual channel mobile phones.
2. Description of the Related Art
Creation of dual modem devices and other technological advances have made it possible for mobile communication devices to utilize more than one transmission channel or mode, such as a data channel, a dispatch channel, and/or a voice channel. These devices are often referred to as dual mode or multi mode devices, which for simplicity are referred to generically hereafter as dual mode devices. Dual mode devices can face a scenario in which one communication channel is active and a different channel wants to come into service. Even short periods of simultaneous dual transmissions can be disallowed for some dual mode device implementations. For example, Federal Communication Commission (FCC) guidelines, such as Specific Absorption Rate (SAR) requirements, can be violated when a mobile device transmits over more than one channel at a time. Antenna diversity, software/firmware infrastructure, service agreements, and other considerations can also limit a mobile device to a single active communication channel at a time.
Simplistic solutions that would completely disable active software or active processes associated with a first channel when switching to a second channel are disadvantageous due to a loss of system state information. That is, an abrupt disconnect between different transmission modes results in a poor user experience. What would be more beneficial, yet which is currently not possible is to gracefully switch back and forth between different transmission channels in a fashion where network registration information and system state information are maintained. To illustrate with an example, a user can be engaged in a data channel operation (i.e., Web browsing), can interrupt this channel to send/receive a dispatch message over a dispatch channel, and then can re-engage the data channel at original point same logical point that was previously being utilized (i.e., can continue browsing the original Web page at the original point).
In dual mode devices, conventional handset software that controls communication sessions and the software that controls transceiving tasks are different software modules. These modules are currently not synchronized at all times, making conventional handset software unsuitable for preventing simultaneous transmission. Another means to prevent simultaneous transmissions while maintaining system state information is to modify network elements. Modifying network elements, however, requires costly and time consuming deployments. Further, it could hamper or constrain future mobile telephony growth areas, such as implementations for redundant networking capabilities.